While the Mozilla Foundation supports a number of projects, its taxable subsidiary the Mozilla Corporation is responsible for only Firefox and Thunderbird. However, it has become increasingly clear that Firefox is the priority. The resources allocated to Firefox dwarf those allocated to Thunderbird and recent projects such as the initiative to improve Mozilla support exclude Thunderbird.

Mitchell outlines three possible options for a new organisational structure for Thunderbird. One is to create a entirely new non-profit, which would offer maximum independence for Thunderbird but is organisationally complex. A second option is to create a new subsidiary of the Mozilla Foundation for Thunderbird, which would keep the Mozilla Foundation involved but may mean that Thunderbird continues to be neglected in favour of Firefox. A final option is to recast Thunderbird as community project, similar to SeaMonkey, and set up a small independent services and consulting company to continue development. However, there are concerns over how the Thunderbird product, project and company would interact.

On his new weblog, lead Thunderbird developer Scott MacGregor has posted his thoughts on the finding a new home for Thunderbird. He states that he favours the third option. Scott explains that this means that Thunderbird would continue to use Mozilla Foundation infrastructure, such as the CVS repository and Bugzilla, and the new company would perform a similar role for Thunderbird as the Mozilla Corporation does for Firefox, developing, releasing and supporting the application.

Update: In the text above, the sentence "While the Mozilla Foundation supports a number of projects, its taxable subsidiary the Mozilla Corporation is responsible for only Firefox and Thunderbird" was potentially misleading. The Corporation provides significant support to projects other than Firefox and Thunderbird in terms of hardware, services and personnel.

It would be more accurate to say that Firefox and Thunderbird are Mozilla products, which means that they get released, distributed and supported as end-user applications by the Corporation. Other applications, such as SeaMonkey and Camino, are Mozilla projects, which are made into products by volunteers or other organisations, if at all.